JP5742480B2 - Castable refractory construction method - Google Patents

Description

The present invention relates to a method for constructing a castable refractory used as a lining material for an industrial furnace and its auxiliary equipment.

In industrial furnaces such as heating furnaces, melting furnaces, heat treatment furnaces, and their ancillary equipment, the lining layer covering the iron skin is roughly composed of a wear layer disposed on the operating surface side and a permanent layer disposed on the back surface thereof. Has been. Also, in recent years, a heat insulating material has been interposed between the permanent layer and the iron skin to reduce the heat dissipated from the furnace body to prevent the temperature drop of the molten metal and to reduce the heat load on the iron skin. Has also been done.

The lining material may be either regular refractories (refractory bricks) or irregular refractories (castable refractories), but castable refractories are used from the viewpoint of ease of construction and labor saving. Often done. However, when a castable refractory layer is formed on a heat insulating refractory such as ceramic fiber, the moisture contained in the castable refractory is sucked into the heat insulating refractory, and the construction quality of the castable refractory deteriorates. There is.

Therefore, in Patent Document 1, a step of attaching an inorganic material that adjusts and absorbs the difference in thermal expansion, a step of applying a water repellency treatment to the inorganic material, and a water repellency treatment are performed on the inner side of the metallic outer shell material (iron skin). An invention of a method for producing an intermediate stalk comprising a step of lining an irregular shaped refractory heat insulating material (castable refractory) on an applied inorganic material is disclosed.

On the other hand, a microporous heat insulating material whose thermal conductivity is generally less than 0.1 W / mK has recently been widely used. This fine porous heat insulating material is almost composed of spherical fine particles of silica SiO ₂ , alumina Al ₂ O ₃ or the like, and the surface of these metal oxides has hydrophilicity. For this reason, water (H ₂ O in a liquid state) is easily infiltrated, and the arrangement of the constituent particles is collapsed by the infiltrated water, so that the heat insulation is greatly deteriorated.

In order to prevent this, when a castable refractory is constructed adjacent to the fine porous heat insulating material, a technology (see Patent Document 2) for providing a protective plate for preventing the movement of moisture between these two, or fine porosity A technique for applying a water-resistant paint to a heat insulating material and / or a castable refractory (see Patent Document 3) is disclosed. In addition, a water repellent treatment is generally performed on the fine porous heat insulating material.

JP 2006-272448 A JP 2003-42667 A JP 2010-236782 A

As described above, in order to prevent deterioration of the construction quality of the castable refractory due to moisture being sucked out from the castable refractory, or in order to prevent the heat insulation performance deterioration of the microporous insulation material to be processed, Water repellent treatment may be applied to the work surface on which the refractory is applied.

However, when castable refractories are applied to a work surface that has water repellency (hydrophobicity), sufficient adhesion does not work between the work surface and the castable refractory, so the castable refractory peels off due to its own weight. May fall. However, when castable refractories are applied to the work surface by the frame pouring method, even if the work surface is subjected to water repellent treatment, it does not hinder the work. In the frame pouring method, a predetermined gap is provided with respect to the work surface, the mold is placed opposite to it, the castable refractory that has been kneaded with water is poured into this gap and allowed to stand, and then cured and removed. It is a method to frame.
In the case of the frame pouring method, the castable refractory poured into the gap is held by the mold until it is cured and cured, so that it does not peel off and fall. Incidentally, in Patent Document 1, in paragraph [0027], “After the water repellent is dried, the inner mold is fitted and the inner mold and the outer cover material to which the heat-expandable sheet material is attached are described in Table 1. An unshaped refractory insulation composed of a mixture was poured while applying vibration. "

However, when installing a castable refractory between the work surface and the wear lining material, it is impossible to install the formwork due to the stud hardware, etc., and the castable refractory is constructed by a construction method other than the frame pouring method. You may have to. In order to construct a castable refractory without using a formwork, it is necessary to have an adhesive force between the construction surface and the castable refractory. Since the adhesive force does not work, the castable refractory peels off from the work surface by its own weight and falls. In particular, when a castable refractory is applied to the lower surface of the skid beam in the walking beam type continuous heating furnace for hot rolling, this phenomenon becomes remarkable.

On the other hand, the present inventors have found that the same phenomenon as described above occurs when a castable refractory is applied to a work surface having excessive hydrophilicity. That is, when castable refractories are constructed on a work surface that is excessively hydrophilic, a water film is formed so that moisture is drawn into the interface between the work surface and the castable refractory to form a castable refractory. Loses its adhesive force and easily falls off the work surface.

The present invention has been made in view of such circumstances, and a castable refractory layer is not formed on the work surface in a situation where a sufficient adhesion force does not work between the work surface and the castable refractory and the formwork cannot be used. It aims at providing the construction method of the castable refractory which can form stably.

The inventors of the present invention have intensively studied a mechanism for generating an adhesive force between a work surface and a castable refractory. As a result, the following findings (1) and (2) were obtained, and based on this knowledge, the invention (3) was conceived.

(1) When the construction surface has water repellency (hydrophobicity), specifically, when the contact angle of water drops on the construction surface is 110 ° or more, castable refractories are constructed on the construction surface. Then, the castable refractory that comes into contact with the work surface is repelled. For this reason, sufficient adhesive force does not work between the work surface and the castable refractory, and the castable refractory easily falls off.
(2) When the construction surface has excessive hydrophilicity, specifically, when the contact angle of water drops on the construction surface is 7 ° or less, when a castable refractory is constructed on the construction surface, Water collects at the interface between the work surface and the castable refractory so as to form a water film. For this reason, the castable refractory loses adhesive force and easily falls off. Moreover, the castable refractory in the vicinity of the work surface loses moisture due to the above phenomenon and cannot secure sufficient construction quality. As a result, castable refractories may fall off.

(3) In order to form a castable refractory layer having a predetermined thickness on the construction surface without using a formwork by ensuring adhesion between the construction surface and the castable refractory, What is necessary is just to provide the layer whose contact angle of a water droplet exceeds 7 degrees and is less than 110 degrees on the outermost surface of the said to-be-constructed surface.

That is, in the construction method of the castable refractory according to the present invention, the surface treatment layer in which the contact angle of the water droplet is more than 7 ° and less than 110 ° on the construction surface where the contact angle of the water droplet is 110 ° or more or 7 ° or less. After forming, a castable refractory is applied on the surface treatment layer.

FIG. 1 is a schematic diagram showing the interfacial tension acting on a water droplet 10 formed on a solid substrate 11 having a horizontal surface. In FIG. 1, the surface tension of the water droplet 10 (water droplet 10 and air 12 acting on the tangential direction drawn from the boundary point toward the surface of the water droplet 10 from the boundary point of the water droplet 10, the solid substrate 11 and the air 12. acting between the interfacial tension gamma _SL, the surface tension of a solid substrate 11 (the solid substrate 11 and the air 12 acting between the interfacial tension) gamma _L, the water drop 10 and the solid substrate 11 which acts between the When the interfacial tension is γ _S , the contact angle θ of the water droplet 10 is an angle between γ _L and γ _SL , and the following equation is established.
γ _S = γ _SL + γ _L · cos θ

In addition, “apply” is a general term for a method of forming a castable refractory layer on a work surface by a method other than the frame pouring method, specifically, glazing, patching, dry spraying, It refers to a method for constructing a castable refractory layer on the work surface by wet spraying or the like.

As described above, when the contact angle of water droplets on the construction surface is 110 ° or more, when the castable refractory is constructed on the construction surface, the castable refractory that comes into contact with the construction surface is repelled. On the other hand, when the contact angle of water droplets on the work surface is 7 ° or less, when a castable refractory is constructed on the work surface, moisture is drawn into the interface between the work surface and the castable refractory. As a result, the castable refractory loses its adhesion and easily falls off. Therefore, in the castable refractory construction method according to the present invention, a surface treatment layer having a contact angle of water droplets of more than 7 ° and less than 110 ° is formed on the work surface.

In the castable refractory construction method according to the present invention, the surface treatment layer is formed by fixing a sheet-like material having a contact angle of water droplets of more than 7 ° and less than 110 ° on the construction surface. You may do it.
Here, the “sheet-like material” refers to a flexible material such as a belt-like shape, a cloth-like shape, or a paper-like shape that has a smaller thickness than the width and length.
“Stick” means that a sheet-like material is placed so as to cover the work surface, and the sheet-like material is fixed on the work surface so that the sheet-like material does not peel from the work surface. To do. Therefore, a sheet-like material may be affixed to the construction surface, or the sheet-like material is tied to the construction surface with a wire such as a thread or wire, or the sheet-like material is fixed to the construction surface with staples or the like. You may do it.

In the castable refractory construction method according to the present invention, a surface treatment layer having a water droplet contact angle of more than 7 ° and less than 110 ° is formed on a work surface having a water droplet contact angle of 110 ° or more or 7 ° or less. Then, since the castable refractory is applied on the surface treatment layer, the adhesion between the work surface and the castable refractory is ensured by the surface treatment layer. As a result, the castable refractory layer is stably formed on the work surface, and the castable refractory does not peel and fall from the work surface.

It is a schematic diagram for demonstrating the contact angle of a water droplet. It is the schematic diagram which showed the shape of the water droplet formed on the to-be-processed surface which has a horizontal surface, (A) is when the to-be-processed surface has water repellency, (B) has high hydrophilicity to the to-be-executed surface. Each case is shown.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.

The construction method of the castable refractory according to the present invention is such that when the castable refractory is constructed on a work surface having a water droplet contact angle of 110 ° or more or 7 ° or less, the water droplet contact angle exceeds 7 ° and 110 °. The surface treatment layer which is less than this is provided on the work surface, and a castable refractory is applied onto the surface treatment layer.

FIG. 2 is a schematic diagram showing the shape of the water droplet 10 formed on the work surfaces 13 and 14 when the water drop 10 is dropped on the work surfaces 13 and 14 having a horizontal surface. As shown in FIG. 2A, when the work surface 13 has water repellency, the contact angle θ of the water droplet 10 increases. On the other hand, as shown in FIG. 2B, when the work surface 14 has high hydrophilicity, the contact angle θ of the water droplet 10 becomes small.

The technical idea of the present invention can be summarized in the following two points.
(A) A surface treatment layer having good adhesion to the castable refractory is formed between the work surface and the castable refractory.
(B) Paying attention to the wettability of the work surface and the surface treatment layer, the wettability of the work surface and the surface treatment layer is quantitatively evaluated by the contact angle of water droplets.

The construction method of the castable refractory according to the present invention is based on the above technical idea, and the contact angle of water droplets is 110 ° or more, and the work surface that is difficult to wet (has water repellency (hydrophobicity)) or the contact angle of water droplets A surface treatment layer having a moderate wettability in which the contact angle of water droplets is more than 7 ° and less than 110 ° between a work surface which is easily wetted (below 7 °) and a castable refractory material. To form.
In the present invention, it is important to secure adhesion between the work surface and the castable refractory, and the contact angle of water droplets in the material constituting the work surface is 110 ° or more or 7 ° or less. But there is no problem.

[Construction surface]
Examples of the contact angle of water droplets on the work surface being 110 ° or more include the following two cases.
(A) After constructing a heat-insulating refractory such as ceramic fiber or calcium silicate-based heat insulation board, when constructing a castable refractory using the heat-insulating refractory as a work surface, water-repellent treatment is performed on the heat-insulating refractory There are many. This is for preventing deterioration of the construction quality of the castable refractory due to the moisture of the castable refractory being sucked out by the heat insulating refractory when the castable refractory is constructed.

(B) After constructing a microporous heat insulating material such as WDS (registered trademark) manufactured by Wacker-Chemie GmbH or microtherm manufactured by Nihon Microtherm Co., Ltd., cast the microporous heat insulating material as a work surface. When constructing a refractory, the fine porous heat insulating material is often subjected to a water repellent treatment. This is to prevent the heat insulation property of the microporous heat insulating material from being lowered due to the moisture of the castable refractory material being absorbed by the microporous heat insulating material when the castable refractory material is applied.

On the other hand, examples of the contact angle of water droplets on the work surface being 7 ° or less include the following two cases.
(A) After constructing a heat-insulating refractory such as ceramic fiber or calcium silicate-based heat insulation board, when constructing a castable refractory using the heat-insulating refractory as a work surface, the heat-insulating refractory is not subjected to water repellent treatment It is conceivable to install a castable refractory using the heat insulating refractory as a work surface. When the water-repellent treatment is not performed on the heat-insulating refractory such as a calcium silicate heat-insulating board, the water-drop contact angle is 7 ° or less because the water-absorbing refractory has high water absorption.
(B) It is conceivable to construct a castable refractory using a fine porous heat insulating material not subjected to water repellent treatment as a work surface.

[Method for Forming Surface Treatment Layer with Water Drop Contact Angle of More Than 7 ° and Less than 110 °]
As a method for forming a surface treatment layer having a contact angle of water droplets of more than 7 ° and less than 110 ° on the surface to be constructed, for example, a sheet-like material having a contact angle of water droplets of more than 7 ° and less than 110 ° is used. There is a method to adhere to the work surface.

As a method of fixing the sheet-like material to the work surface, there is a method in which an adhesive is applied to one surface of the sheet-like material and the sheet-like material is attached to the work surface by the adhesive force. As the sheet-like material used in this construction method, for example, generally widely available adhesive tapes can be used. Among them, cloth adhesive tapes based on cloth made of sufumofu, polyester, polyethylene, etc. are cost and work. From the viewpoint of sex.

In addition to adhesives, sheet-like materials can be sewn, wound, or tied to the work surface with a wire such as thread or wire, or the sheet-like material can be fixed to the work surface with staples. The method of doing etc. can be considered. Of course, an adhesive and a method such as a wire may be used in combination.

[Castable refractory application method]
Hereinafter, a method for applying the castable refractory will be described with an example.
In each of the following methods, the castable refractory layer is held on the work surface by the adhesion of the castable refractory to the work surface on which the surface treatment layer is formed. Moreover, when a stud hardware, a hanger brick, etc. are used together, these contribute to holding | maintenance of the castable refractory layer after curing hardening.
(A) Sprinkle coating method Castable refractories that have been kneaded with water are placed on the surface to be constructed, and castable refractories are formed to spread out the castable refractories using scissors or fingers. Form. Then, the castable refractory layer is cured and cured by standing still.

(B) Patching construction method Water-kneaded castable refractory adjusted to clay (generally called plastic refractory) is placed on the work surface, and the caster refractory is spread using a rammer, fingers, scissors, etc. Mold. Then, the castable refractory layer is cured and cured by standing still.

(C) Dry spraying method Castable refractory powder for dry spraying is cut out at a predetermined speed into the air flow for pumping, and spray nozzle for spraying dry castable refractory powder via a hose. To send to. And immediately before spraying the dry sprayable refractory powder from the spray nozzle, by adding a predetermined proportion of moisture to the dry sprayable refractory powder and spraying on the work surface, A castable refractory layer is formed on the work surface. Then, the castable refractory layer is cured and cured by standing still.

(D) Wet spraying method After the wettable sprayable refractory is kneaded with water, the wettable sprayable refractory is cut out at a predetermined speed into the air flow for pumping, and then wet sprayed via a hose. Attached castable refractories are fed toward the spray nozzle. Then, immediately before spraying the wettable sprayable refractory from the spray nozzle, a predetermined proportion of the curing accelerator is added to the wettable castable refractory and sprayed onto the work surface. A castable refractory layer is formed on the surface. Then, the castable refractory layer is cured and cured by standing still.

[Measurement method of water contact angle]
The contact angle of the water droplet may be measured using JIS R3257: 1999 “Testing method for wettability of substrate glass surface”. In the present invention, “6. The contact angle of water droplets measured by the method described in “Still Drop Method” is used.
In addition, for work surfaces with water absorption, the following procedures are applied mutatis mutandis to paragraphs 4.1.2 and 4.1.4 of JIS R2205-1992 “Measurement method of apparent porosity / water absorption / specific gravity of refractory bricks”. After adjusting the sample (surface to be constructed) by the above method, the contact angle is measured by the sessile drop method described in JIS R3257: 1999.
(1) Saturate the construction surface by sufficiently spraying distilled water onto the construction surface with water absorption.
(2) The surface to be constructed is wiped with a poultice (a cloth that has been sufficiently wetted with distilled water in advance and then thoroughly squeezed with water) to remove surface water droplets on the surface to be constructed.
(3) Immediately measure the contact angle of the work surface by the sessile drop method described in JIS R3257: 1999.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the above-described embodiments, and is considered within the scope of the matters described in the claims. Other embodiments and modifications are also included. For example, in the said embodiment, the example of the surface of a to-be-processed surface whose water contact angle is 110 degrees or more or 7 degrees or less, and the method of providing the surface treatment layer whose water contact angle is more than 7 degrees and less than 110 degrees However, it goes without saying that the present invention is not limited to these examples.

In order to verify the effect of the construction method of the castable refractory according to the present invention, a refractory lining construction comparative test was performed on a skid beam of a walking beam type continuous heating furnace for hot rolling. A list of tests performed is shown in Table 1. Each contact angle shown in the table indicates a value measured by the above-described [Method of measuring contact angle of water droplet].

The object of refractory lining is a water-cooled pipe of a skid beam. After constructing the heat insulating material described in the column “Construction surface” of Table 1 on the outer surface of the water-cooled pipe, the surface treatment described in the “Surface treatment tank” column of the same table is applied to the surface of the heat insulating material. Carried out. Thereafter, a heat-insulating castable refractory was applied on the surface treatment layer, and the construction results were evaluated.

Note that castable refractories that do not use a formwork include glazing, patching, dry spraying, and wet blasting. Of these, the most severe requirement for adhesion is glazing. In general, the greater the amount of water added for kneading, the greater the adhesion to the work surface. However, in the case of dry-type spraying, where the amount of water added is higher than that of glazing, the castable refractory layer is formed in several layers, the evaporation of water is accelerated by the air flow for spraying, and the castable refractory layer is formed. The requirement for adhesion is not so strict, for example, the time from curing to curing curing to a certain extent is as short as several seconds to several minutes. For this reason, as the heat insulation castable construction method to the construction surface in this comparative test, the glazing construction was adopted.

In all the examples, the castable refractory layer was stably formed on the work surface, and the castable refractory was not peeled off from the work surface. Specifically, in Examples 1 and 4, the heat-insulating castable refractory material tends to stick to the surface more than the work surface during coating, and the thickness of the heat-insulating castable refractory layer is limited to about 15 to 20 mm. It was. For this reason, the evaluation after construction of Examples 1 and 4 was evaluated as ◯. Moreover, Examples 2 and 3 had good workability, and the thickness of the heat-insulating castable refractory layer could be easily set to 40 mm. For this reason, the evaluation after construction of Examples 2 and 3 was evaluated as ◎.
On the other hand, since the heat insulation castable refractory dropped off from the surface to be constructed and could not be constructed in all the comparative examples, the evaluation after the construction was x.

10: Water droplet, 11: Solid substrate, 12: Air, 13, 14: Work surface, θ: Contact angle

Claims (2)

After forming a surface treatment layer having a water droplet contact angle of more than 7 ° and less than 110 ° on a work surface having a water droplet contact angle of 110 ° or more or 7 ° or less, the castable refractory is formed on the surface treatment layer. A castable refractory construction method characterized by applying 2. The castable refractory construction method according to claim 1, wherein the surface treatment layer is formed by fixing a sheet-like material having a contact angle of a water droplet of more than 7 ° and less than 110 ° on the construction surface. A castable refractory construction method characterized by

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